Erb's Palsy

- Discussion:
- most common birth related neuropraxia (about 48%);
- lesion of C5 & C6 roots are usually produced by widening of the head shoulder interval (in some cases C7 is involved as well);
- may occur at birth, producing lesion of axillary nerve, musculocutaneous, & suprascapular nerve;
- muscles most often paralyzed are supraspinatus and infraspinatus because the suprascapular nerve is fixed at the suprascapular notch; (Erb's point)
- in more severely affected patients deltoid, biceps , brachialis, and subscapular is affected (C5 and C6 );
- chronic internal rotation contracture leads to secondary osseous changes (increased glenoid retroversion) and posterior subluxation of the shoulder;
- mean glenoid retroversion on the injured side is approximately 26 deg vs 6 deg on the normal side;
- w/ increasing retroversion, there will be associated subluxation, dislocation (w/ development of false glenoid), and w/ increasing severity,
there will be flattening of the humeral head;
- diff dx:
- pseudoparalysis resulting from clavicle and humerus fractures or osteomyelitis must be excluded;
- see: clavicular frx in infants;
- prognosis:
- brachial plexus injuries range from mild neuropraxia w/ early recovery to complete disruption with no potential for recovery;
- fortunately, between 80% to 90% of children with such injuries will attain normal or near normal function;
- attempt to determine whether the lesion is preganglionic or post-ganglionic;
- preganglionic lesions have a worse prognosis (avulsion of the roots from the cord which disrupts the sympathetic chain)
- preganglionic lesions may be more common w/ breech deliveries;
- persistent Horner's sign (ptosis, myosis, and anhydrosis) is a sign of proximal injury - preganglionic injury;
- preganglionic injuries are unlikely to recover;
- follow upper trunk innervation:
- affected children who show clinical or EMG evidence of biceps function before 6 months of age have near normal to excellent function;
- in addition to biceps, follow motor strength of shoulder abduction, wrist extension, and thumb extension;

- Exam:
- arm cannot be raised, since deltoid (axillary nerve ) & spinati muscles (suprascapular nerve) are paralyzed;
- elbow flexion is weakened because of weakness in biceps & brachialis;
- if roots are damaged above their junction, paralysis of rhomboids and serratus anterior is added, producing weakness in retraction and protraction of scapula;
- after the age of 6 months, contractures begin to develop (adduction and internal rotation contractures);
- paralytic supination deformity of the forearm;
- develops from the imbalance between the supinator and the paralyzed pronator muscles (pronator teres and pronator quadratus);
- passive correction of the deformity is possible initially, but becomes fixed w/ later growth as the interosseous membrane becomes fixed;
- chronic changes include volar subluxation of the distal end of the ulna or proximal head of the radius;

- Management:
- during first six months gentle ROM exercises are necessary to retain external rotation & abduction at the shoulder;
- EMG will help distinguish reversible vs irreversible nerve damage and will help map out anatomy of the injury;
- nerve grafting controversies:
- children who show no clinical or electromyographic evidence of biceps, muscle function at age 6 months
in patient w/ C5-6 brachial plexus palsy have a poor prognosis for functional recovery;
- these pts should undergo early brachial plexus exploration and nerve grafting to improve function of dennervated muscle groups;
- other authories recommend nerve grafting before 6 months of age, noting that after 6 months, muscle contractures occur due to unopposed muscle forces;
- release of contractures:
- indicated for patients w/ internal rotation & adduction contraction of the shoulder;
- chronic internal rotation contracture leads to secondary osseous changes (increased glenoid retroversion) and posterior subluxation of the shoulder;
- early operative management includes: release of subscapularis (and in some severe cases release of anterior joint capsule and pectoralis major);
- soft tissue release is performed inorder to regain external rotation and to prevent pathologic osseous changes;
- it is important to note that aggressive anterior releases may result in anterior instability;
- some authors feel that the pectoralis does not usually result in contracture and does not require release;
- technique of release of subscapularis from the scapula:
- as compared to releasing the subscapularis off of the humerus, this technique avoids anterior instability;
- patient is placed in the lateral position;
- make a longitudinal incision along the lateral border of the scapula;
- identify the fibers of the latissimus muscle (over the lateral aspect of the scapula), and retract it inferiorly;
- subscapularis is elevated off of the anterior surface of the scapula;
- increase in external rotation demonstrates adequacy of the release;
- avoid injury to the subscapular artery and nerve at the scapular notch and at the anteromedial aspect of the glenoid neck;
- splint is applied to maintain the arm in abduction and external rotation for 3 months, followed by 3 months of night splinting;
- tendon transfers:
- indicated to counteract the shoulder adductors and internal rotators;
- generally performed prior to age 7 yrs;
- latissimus dorsi may be transfered to the rotator cuff / greater tuberosity (augments external rotation power);
- in the report by Edwards TB, et al, a retrospective study of the results of latissimus dorsi and teres major transfer in the treatment of Erb's
palsy was conducted in 10 patients;
- all patients underwent release of the pectoralis major and transfer of the latissimus dorsi and teres major tendons to the rotator cuff
at a mean age of 7 years and 2 months;
- active shoulder abduction improved from a mean of 72 degrees preoperatively to 136 degrees postoperatively;
- postoperative shoulder active external rotation averaged 64 degrees;
- all but one patient were satisfied with the final outcome;
- ref: Results of latissimus dorsi and teres major transfer to the rotator cuff in the treatment of Erb's palsy.
- posterior glenohumeral subluxation:
- as w/ DDH, aggressive treatment early on may reverse the deformity, where as older children may require derotational osteotomy;
- limitation of external rotation;
- for older children (older than 5 yrs of age) with fixed bony adaptive changes, proximal humeral external rotation osteotomy can be considered;
- in late cases, w/ a deficient posterior glenoid consider humeral derotational osteotomy;
- forearm pronation deformity:
- correction of the supination deformity requires early intervention;
- consider brachioradialis transfer through the interosseous membrane;
- ref: A surgical technique for pediatric forearm pronation: brachioradialis rerouting with interosseous membrane release.

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Orthopaedics and the US Military

Text Author

Dr. Wheeless enjoys and performs all types of orthopaedic surgery but is renowned for his expertise in total joint arthroplasty (Hip and Knee replacement) as well as complex joint infections. He founded Orthopaedic Specialists of North Carolina in 2001 and practices at Franklin Regional Medical Center and Duke Raleigh Hospital.